Trying to run install script and it downloads file

Okay so I am trying a fresh install of wordpress on a clients site.
Ive uploaded the files on the the server using FTP ( filezilla), and edited the wp-config.php file matching the new databsase settings aswell. Now the next step is to run the install script I believe but when I type the url in ( mysite.co.uk/wp-admin/install.php ) it downloads the install.php file.

Im thinking that im seeing a directory listing rather than a web page which is why it is downloading the file i type in the URL. Now I think it is an issue regarding .htacces but I do not know how to create it nor what to put in it in order to point to the index.php by default and ?

Any ideas thanks?